package com.itheima.d5_interface;

public interface Sing {
    //常量: 可以将 public static final 省略
    //public static final double PI = 3.14;
    double PI = 3.14;

    //抽象方法: public abstract可以省略的
    //public abstract void singASong();
    void singASong1();
    void singASong2();
}
